In March 1982, Argentinean scrap metal dealers landed on British sovereign territory - the island of St. Georgia in the South Atlantic - and raised the Argentine flag. This was the base for an old and defunct whaling station and the gesture seemed to be more for posturing as opposed to anything more sinister as the island had little importance - be it economic or strategic. However, it was British territory and what the Argentineans did was illegal under international law. A group of Royal Marine Commandos was dispatched to remove the 'invaders'.
On April 2nd, 1982, a large Argentine military force landed on the Falkland Islands and occupied them. To the British, this was a flagrant violation of international law. Despite American intervention at a diplomatic level led by Secretary of State Al Haig, the Argentine military junta led by General Galtieri refused to take their men off the island. This led to a British military response.
This would be the standard British explanation as to why the war stated - the illegal occupation of the Falklands by the Argentine military and the refusal of the Argentine government to remove their men sent there.
However, in Argentina, the move into the Malvinas, as the Falklands are known in Argentina, would have had a different slant. The Argentine junta argued that the British 'occupation' of the islands was a throwback to the days of the British Empire whereby Britain had used its military might - especially its navy - to take land which simply did not belong to London. The argument held by the Argentine government and seemingly by many people in Argentina, was that the islands, being just 200 miles to the east of the Argentine mainland, belonged to the nearest country of any importance - Argentina.
At the time of the invasion, Argentina was experiencing chronic economic problems, primarily centred on a severe rate of inflation. A successful overseas venture would have served to patriotically rally the country around the government and act as a distraction to what was happening at home.
From Britain's standpoint Argentina was guilty of violating international law and the failure of diplomacy meant that the only route Britain could go alone was a military one. From Argentina's standpoint, Britain was resting on her imperialist past and occupying land that logically could not be British territory.
As neither was willing to back down despite the diplomatic manoeuvres that occurred, war was inevitable.